So yesterday I added in an earthquake event. It's a pretty simple thing, every once in a while there will be an earthquake that shakes things up and will damage things nearby. However because there are so many systems that work together it has a bigger impact than you'd expect.

Everything in the area getting damaged a little bit will probably be minor to the player, except when they are foolishly running around with low health. It will usually flatten fragile things like barrels and crates. Really unstable things are going to cause problems, like exploding barrels and energy vortexes will go boom. Of course this can set off a chain reaction of other unstable things.

The damage will also wake up any monsters in the area. Any monster hiding and waiting to ambush the player will likely come out and be a little bit upset. I guess this could be a good or bad thing for the player. It will screw up their ambush, but you might have more monsters to deal with than you would have otherwise. This will also effect any monsters scared of pain who have low morale.

Next, if close enough to the player, it will shake their screen around. This doesn't really change any gameplay but it does feel pretty cool.

If the earthquake hits near a weak area in the dungeon (cracks, leaks, etc) it might very well bring down the ceiling on any poor sucker below it. Hopefully for your sake, that's the monsters and not you. Even if it doesn't cause cave-ins, it will likely weaken the area around you making it more susceptible to further damage.

World modifiers are impacted because the Unstable, Explosion Hazard, and Chaos world modifiers now have more earthquakes than usual.

What manner of scale are you rigging up for them anyways? I would imagine a Richter'ish variety up to "insert disaster movie here" level would surely help keep players on their toes as to seeing them in their time in a given world.

Compared to the real world they are pretty small and localized, lasting only a few seconds. However, in the real world you don't tend to adventure in caves and dungeons with dangerous creatures and around lots of things that can blow up.